1. Field of the Invention
The present invention relates to a base station apparatus of a CDMA mobile communication system and, in particular, to a base station apparatus that has a packet communication function for performing packet communication with a terminal that communicates with a base station.
2. Description of Related Art
This kind of base station transmits packet data for an arbitrary user (terminal; communication node) using a channel exclusively used for packet communication.
In the packet data transmission, an order for transmitting the packet data and user information (an encoding system, a modulation system, the number of codes per user, etc.) concerning the packet data are selected and determined.
For example, JP-A-2004-166123 discloses a method of controlling user information (an encoding system, a modulation system, etc.) for respective users.
A base station acquires quality information such as an SIR (Signal-to-Interference power Ratio) and a BLER (Block Error Rate) in a downlink (a direction from a base station to a terminal) using a channel in an uplink (a direction from a terminal to a base station) and controls an order of transmission to the respective users and the user information using this quality information.
However, when the base station transmits packet data to the terminal, the terminal transmits response data to the base station after a predetermined period elapses. Thus, the base station does not receive a signal from a certain user for some period. This point is not taken into account in JP-A-2004-166123.
Therefore, if hardware (correlators and complex multipliers) for processing a reception signal is fixedly allocated to the respective users, these kinds of hardware are not effectively used in the period in which the base station does not receive signals from the users.